See how to install a tubeless tire:
Faster and More Stable
According to wheel category manager Jason Fowler, Zipp’s goal with the new line of Carbon Clincher Tubeless Disc brake wheels was to achieve lower aerodynamic drag and side force with 28mm tires than with those that are 25mm. (Laugh in the face of wind? Check out our new Elements of Cycling Tee, featuring that one aspect of rides we all love to hate.)
They got part of the way there. In the majority of the wind conditions the rider is going to see the 202 and 303 Carbon Clincher Tubeless Disc brake are faster overall, with lower side force with a 28mm tire than with a 25mm tire—and faster than the previous generation of the wheel with a 28mm tire.
The 404 and 808 Carbon Clincher Tubeless Disc brake, however, remain slightly faster with a 25mm tire than they do with a 28mm. But again, with 25mm tires, the new-generation wheels are faster, with lower side force, than the previous generation with 25mm tires.
Whether you pay for the Firecrest or NSW version, rim height and width (internal and external) are the same. Depths are the same as rim brake versions of the wheels: 202 with 32mm, 303 with 45mm, 404 with 58mm, and 808 with 82mm.
However, the disc tubeless versions are wider than the rim-brake versions, and wider than the previous generation of Zipp’s disc-brake wheels. The new 202 and 303 rims have a 28.9mm external width and are 21mm internally; the new 404 and 808 rims have a 26.4mm external width and are 19mm internally.
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The deeper rims are narrower for two reasons. They’re more likely to be used in a traditional road setting with narrower tires, so the additional width is not necessary to support a wide tire; and according to Zipp’s testing, at these depths, the wheels are more aerodynamic and more stable at this dimension than if they were wider.
Zipp’s reasons for embracing tubeless are not unique. The company’s wheel product manager, Bastien Donze, relayed five benefits, but three are related to lower tire pressure: better cornering grip, more comfort, improved rolling resistance.
The first two need no further explanation, but the third may seem counter-intuitive. Lower pressures can reduce rolling resistance because the tire can deform and absorb smaller bumps and ripples instead of needing to roll up, over, and down the other side. Also, with tubeless, there is of course no tube, which means energy-sapping…